This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. This project aims at determining crystal structures of protein translocation components. The goal of the project is to get insight into the mechanism by which proteins are moved through the membrane. To this end, we are trying to get structures of the channel on its own, of the channel bound to its partners (the ATPase SecA, the ribosome, or the Sec62/63p complex), and of the channel in action with a translocating polypeptide chain. In the past, we have determined the structures of the protein translocation channel, the SecY complex, from an archaebacterium, as well as the structures of the ATPase SecA bound to the SecY channel.